EIN Guide for Your Connecticut LLC

An Employer Identification Number is a nine-digit number the IRS issues to identify a business for federal tax purposes. Think of it as a Social Security number for your company. It is issued by the federal government — the IRS — and has nothing to do with the Connecticut Secretary of the State. Forming your LLC in Connecticut and getting an EIN are two separate steps with two different agencies.

The order that makes sense

Form the LLC first, then get the EIN. The IRS asks for your LLC's legal name and formation details when you apply, so having the Articles of Organization processed first keeps everything consistent. Applying for the EIN before the LLC exists can create a mismatch between the name on the EIN and the name on your state record.

What you use the EIN for

• Opening a business bank account (most banks require it).
• Hiring employees and handling payroll taxes.
• Filing federal tax returns for the LLC.
• Applying for certain licenses and setting up accounts with vendors and payment processors.

Not every single-member LLC is legally required to have an EIN, but most owners should get one anyway. Here is how to tell.

You are required to have an EIN if

• Your LLC has more than one member. A multi-member LLC is taxed as a partnership by default and must file a partnership return, which requires an EIN.
• You have employees. Payroll tax reporting requires an EIN.
• You have elected to have the LLC taxed as an S-corporation or C-corporation.
• You need one for certain federal excise taxes or other specific IRS requirements.

You should probably get one even if not required

A single-member LLC with no employees can technically use the owner's Social Security number for federal taxes. But there are good reasons to get an EIN anyway:

• Banking. Most banks require an EIN to open a business account, and a separate business account is essential for preserving your LLC's liability protection.
• Privacy. Using an EIN keeps your Social Security number off vendor forms, contracts, and paperwork.
• Growth. If you later hire or add a member, you will need one anyway — getting it now avoids a scramble.

For nearly every Connecticut LLC, the EIN is worth getting from the start.

The IRS issues EINs directly, for free, and the fastest route is online.

The online application

Apply through the IRS EIN Assistant at IRS.gov. The application takes about ten minutes, and if it goes through, the IRS issues the EIN immediately — you can download the confirmation letter and use the number the same day. A few practical notes:

• The online tool is available during specific hours (generally business hours in U.S. time zones), not around the clock.
• You must complete the application in one session; it does not save partway through.
• The person applying is the "responsible party" — an individual who controls the LLC — and the IRS limits how many EINs one responsible party can obtain per day.

What you will need

• Your LLC's exact legal name as filed with Connecticut.
• The formation state (Connecticut) and the LLC's address.
• The responsible party's name and their Social Security number or ITIN.
• Basic information about the LLC's structure and why you are applying.

Beware paid "EIN services"

The EIN itself is free from the IRS. Some third-party sites charge a fee and present it as though you are paying for the EIN — you are really paying them to fill out a free form. If you value having someone handle it, that is a fine choice, but know that the underlying number costs nothing directly from the IRS.

The online application requires the responsible party to have a U.S. Social Security number or ITIN. That leaves out some foreign owners, but there is still a path.

Form SS-4 by fax or mail

If you do not have an SSN or ITIN, you cannot use the online tool. Instead, you complete Form SS-4 — the paper EIN application — and submit it to the IRS by fax or mail. This route is slower than the instant online issuance; fax responses typically take a few business days, and mail takes longer.

What to expect

• Fill out Form SS-4 carefully; errors cause delays.
• For the responsible party without an SSN or ITIN, follow the current IRS instructions for that field rather than leaving it blank incorrectly.
• The IRS returns your EIN once it processes the form. Keep the confirmation.

This is a common situation for non-U.S. residents forming a Connecticut LLC, and it is entirely workable — it just takes patience and a correctly completed SS-4.

Getting the number is not the end. A few things follow.

Store the confirmation letter

The IRS issues an EIN confirmation (the CP 575 for a fresh online issuance). Save it. Banks and agencies sometimes ask for it, and if you lose the number later, retrieving it from the IRS is more of a hassle than keeping the letter from the start.

Use it consistently

Use the EIN — not your Social Security number — on business bank accounts, tax filings, and business paperwork. Consistent use is part of keeping the LLC a genuinely separate entity, which supports the liability shield.

Connecticut tax registration is separate

The EIN is federal. If your Connecticut LLC needs to collect sales and use tax or has other state tax obligations, you register separately with the Connecticut Department of Revenue Services. The EIN identifies you federally; state tax accounts are their own registrations. Do not assume having an EIN handles your Connecticut tax setup — it does not.

How Mainstay Filing helps

As part of getting your Connecticut LLC set up, we can point you through the EIN process so it is done in the right order and with the right information matching your state filing. We are a filing service, not a tax advisor — for questions about how your LLC should be taxed or whether to elect S-corp treatment, talk to a CPA. What we make sure of is that the formation and federal-ID steps line up cleanly so your banking and tax setup go smoothly.